Problem: What do the following two equations represent? $-4x+3y = 4$ $20x-15y = -20$
Explanation: Putting the first equation in $y = mx + b$ form gives: $-4x+3y = 4$ $3y = 4x+4$ $y = \dfrac{4}{3}x + \dfrac{4}{3}$ Putting the second equation in $y = mx + b$ form gives: $20x-15y = -20$ $-15y = -20x-20$ $y = \dfrac{4}{3}x + \dfrac{4}{3}$ The above equations turn into the same equation, so they represent equal lines.